Single-walled Carbon Nanotube Induction Of Rat Aortic Endothelial Cell Apoptosis: Reactive Oxygen Species Are Involved In The Mitochondrial Pathway

Oxidative stress is a major factor contributing to endothelial cell damage. Single wall carbon nanotubes (SWCNTs) have oxidative properties; however the oxidative effects of SWCNTs on endothelial cells are not fully understood. In the present study, we investigated the effects of oxidative stress induced by SWCNTs on rat aortic endothelial cells (RAEC). Various markers of cellular damage were assessed, such as Reactive oxygen species (ROS), non-enzymatic antioxidant glutathione (GSH), superoxide dismutase (SOD) activation, DNA damage and protein damage. Our findings suggest that RAEC endured oxidative damage following SWCNT exposure. Additionally, it was found that as SWCNT concentration increased, so did the stress protein, heme oxygenase-1 (HO-1) and the inflammatory factor:tumor necrosis factor (TNFa), expression levels. These changes may induce RAEC damage, and result in many serious diseases.We previously found that 200μg/mL of single-walled carbon nanotubes induce apoptosis in rat aorta endothelial cells. The current study aimed to determine the signaling pathway involved in this process. We found that reactive oxygen species generation was involved in activation of the mitochondria-dependent apoptotic pathway, Oxidative stress is considered to be a major factor contributing to the damage of endothelial cells, but the study of oxidative aspects of SWCNTs to endothelial cells are limited, In the present study, we investigated the effects of oxidative injury of RAECs induced by SWCNTs from various aspects, including biochemically index, esimmunity indexes, DNA damage, protein damage and so on. These results show that the oxidative damages were certainly happened to RAECs. When exposed to SWCNTs, the nonenzymes antioxidant GSH worked earlier than the SOD to defense the oxidative stress by depletion of itself. We also found that with SWCNTs concentration increased, the stress protein HO-1 and the P53 expression level also rose. These changes may induce many different damages to RAECs and result in apoptosis, the finding of apoptosis was supported by a number of morphological and biochemical hallmarks, including chromatin condensation, internucleosomal DNA fragmentation, and caspase-3 activation.In conclusion, our results demonstrate that single-walled carbon nanotubes induce apoptosis in rat aorta endothelial cells and that reactive oxygen species are involved in the mitochondrial pathway.